Process for compensating eccentricities and imbalances of rotating parts

ABSTRACT

In order to permit a fast, precisely centric fastening of rotating tools, such as drills or milling tools in clamping sleeves, of such clamping sleeves or of workpiece holding devices, such as clamping chucks  4  in spindles  1  of turning machines, respective holding surfaces  9/10, 23/24  are provided in the respective parts to be connected with one another with profiles  11, 12, 25, 26  which are coordinated with one another in pairs and which each have at least two wedges  13, 15 . The wedges rise over imaginary cylindrical reference surfaces  14, 16  radially toward the outside and inside and each drop again steeply onto the reference surfaces and are offset in the circumferential direction by identical angles and have a joining gap in a joining position.

This application is a division of application Ser. No. 08/883,227, filedJun. 26, 1997 now U.S. Pat. No. 6,053,508.

BACKGROUND AND SUMMARY OF THE INVENTION

This application claims the priority of German application 196 25 553.8filed in Germany on Jun. 26, 1996, the disclosure of which is expresslyincorporated by reference herein.

The invention relates to a device for the centric and/or imbalance-freeholding of workpieces or tools on a spindle of a machine tool by meansof centric holding surfaces.

For example, in turning machines having a spindle, tools are received inexchangeable clamping sleeves or workpieces to be machined are receivedin clamping chucks and these, in turn, are received in holding devicesof the spindle on cylindrical holding or clamping surfaces which arecentric with respect to the axis of rotation of the spindle. Also, inthe case of a high-precision manufacturing, these holding or clampingsurfaces have an unavoidable eccentricity with respect to their axis.When receiving a tool in a clamping sleeve or a workpiece in a clampingchuck and the clamping sleeve or the clamping chuck in the spindle,these eccentricities are added up depending on the respective accidentalangular position of the parts in a mutually reinforcing or reducingmanner.

In other cases, the mentioned parts also have unbalanced masses which,when being received in the spindle, also add up in a reinforcing orreducing manner and, particularly, in the case of high rotationalspeeds, lead to vibrations or machining faults.

It is an object of the invention to provide a simple possibility forrapidly inserting a tool in a clamping sleeve, a workpiece in a clampingchuck and a clamping sleeve or a clamping chuck in a spindle of aturning machine and removing it and holding it securely.

The invention achieves this object by providing an arrangement of theabove-mentioned type wherein device holding surfaces are provided withprofiles which are coordinated with one another in pairs and which eachhave at least two wedges which rise over imaginary cylindrical referencesurfaces radially toward the outside or toward the inside and each againdrop steeply back to the reference surfaces, are offset by the sameangles in the circumferential direction and have a joining gap in ajoining position.

Because of the joining gap and the wedges arranged around thecircumference of the holding surfaces, the tool can be inserted in theclamping sleeve, the workpiece can be inserted in the clamping chuck andthese can, in turn, be inserted in the spindle and by a rotating about afraction of a rotation can be fastened by means of a frictionalengagement.

Particularly when three wedges are arranged to be offset with respect toone another by the same angles, a very good centering effect can beobtained.

In particular, when the number of the wedges is increased to, forexample, six, there is the advantage that, in the angularly offsetstarting positions corresponding to the number of wedges the parts areinserted into the respective assigned holding device and are connectedwith it in a frictionally engaged manner by rotating. In the case of aflat slope, a rotational frictional engagement of up to 30° is possible.In the case of, for example, six wedges on the circumference, sixdifferent positions are obtained for the fastening which each extendover up to 30°. When the angular positions of the eccentricities orunbalanced masses of two respective parts to be connected are known withrespect to a respective starting position, the parts can be joined insuch a mutual angular position and rotated into the frictionalengagement that the eccentricities or unbalanced masses are largelydiametrically opposite with respect to the axis of rotation of thespindle. As a result, it is achieved that the eccentricities or theunbalanced masses compensate one another as much as possible up to aremaining minimum.

The minimal number of wedges around the circumference of the holdingsurfaces is two—which ensures a secure holding and, particularly whenthe surfaces of the wedges according to the invention follow the courseof a logarithmic spiral and are therefore disposed flatly against oneanother in all angular positions with respect to one another, offers ahigh centering precision in the respective holding device.

The flatter the slope of the wedges in the profile pairings, the largerthe angle about which the parts in the frictional engagement can berotated into a position of an optimal compensation of the eccentricitiesor of the unbalanced masses.

The width of the wedges is selected such that the required torque can besensed and transmitted during the work of the tool or during themachining of the workpiece. The slope direction of the wedges isadvantageously such that the frictional engagement has the tendency ofbeing increased during the machining.

Furthermore, the wedge-shaped profiles have the advantage that they actas an overload protection particularly during the holding of a tool.Specifically, if the slope of the wedges and/or the length of the wedgesis low in the circumferential direction, the wedges may jump over in thecase of an extreme rise of the moment of resistance; that is, thehighest elevations of the wedges of a profile pairing slide over oneanother. This limits the rise of the contacting moment and a break isavoided.

It is preferably provided in this case to displace a jumping-over ofprofile pairings between a tool and the clamping sleeve bycorrespondingly selecting the slopes in order to avoid damage to theholding device on the spindle.

An advantageous slope of the wedges depends, among other things, on thediameter of the profiling. When the diameters are small, the slopes arehigher and are in the range of from 1:50 to 1:200. When the diametersare large, the slopes may be reduced to 1:500.

The figures of the drawing schematically show the embodiments of theinvention on a turning machine and in the form of a clamping chuck, aclamping sleeve and a tool. It is understood that the invention can alsobe used on many other devices.

Other objects, advantages and novel features of the present inventionwill become apparent from the following detailed description of theinvention when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal sectional view of a receiving device of aclamping chuck constructed according to a preferred embodiment of theinvention;

FIG. 2 is a cross-sectional view in the plane A—A of FIG. 1;

FIG. 3 is a schematic view illustrating the principle of thecompensating of eccentricities or unbalanced masses according to theinvention;

FIG. 4 is a longitudinal sectional view of the receiving device of atool constructed according to another preferred embodiment of theinvention; and

FIG. 5 is a longitudinal sectional view of yet another embodiment of theinvention for receiving a tool.

DETAILED DESCRIPTION OF THE INVENTION

As illustrated in FIG. 1, the spindle, for example, of a turningmachine, is disposed in two roller bearings 2—their known drive notbeing shown for reasons of clarity. At the free end, the spindle 1carries a pot-shaped holding device 3 for receiving a clamping chuck 4.The clamping chuck 4 is of a known construction, which is therefore notdescribed in detail, and clamps a workpiece 6 by means of its jaws 5.The workpiece 6 selected as an example has a cylindrical form and, forexample, is to be turned on its circumference by means of turning tool7.

The cylindrical holding surface 9 of the holding device 3 and the alsocylindrical holding surface 10 of the clamping chuck 4 are provided withprofiles 11 and 12 whose construction is illustrated in FIG. 2. Theprofile 11 on the clamping chuck 4 is formed by wedges 13 which, over animaginary, dash-dotted, cylindrical reference surface 14, rise with aslight slope of, for example, 1:100 which, for reasons of clarity isshown here to be very magnified, and which then steeply drop down againto this reference surface. Correspondingly, the wedges 15, which formthe profile 12 on the holding surface 9 of the holding device 3, projectover an imaginary cylindrical reference surface 16 with a slightlylarger diameter than that of the reference surface 14 toward the inside.The illustrated example shows three wedges 13, 15 which each extend over120°. The wedges 13, 15 or their surfaces therefore form mutuallycoordinated profiles 11 and 12 in the holding device 3 or on theclamping chuck 4. Except in the very magnified representation of FIG. 2,the profiles are indicated only in a dash-dotted manner in the otherfigures because the height of the wedges is so low that they would notbe recognizable.

In a starting position in which the steep slopes of the wedges restagainst one another, a gap exists between the surfaces of the wedges 13,15 which is used as a joining play and which permits the introduction ofthe clamping chuck 4 into the holding device 3.

A once determined angular position of an eccentricity or of an imbalanceof the holding device 3 of the spindle 1 is indicated, for example, onthe edge of the holding device by means of a marking 17. Likewise, theangular position of a respective imbalance or eccentricity of theclamping chuck 4 to be determined is noted on the latter by means of amarking 18.

For inserting the clamping chuck 4 into the holding device 3, whileutilizing the joining gap a-d observing the markings 17 and 18, theclamping chuck 4 is pushed into the holding device 3 and, in therepresentation of FIG. 2, is rotated counterclockwise until, when theclamping chuck is rotated into the frictional engagement with theholding device 3, the marking 18 is approximately opposite the marking17 on the receiving device 3—depending on the arrangement of themarkings directly or with respect to the axis of rotation 19 of thespindle 1. In this case, the surfaces of the wedges 13 on the clampingchuck 4 and of the wedges 15 in the holding device 3 will come to restagainst one another and slide on one another in the frictionalengagement while the contact pressure increases. In this case, thedirection of the slope of the wedges 13, 15 is such that this frictionalengagement is increased when the workpiece spindle 1 is rotated in theworking rotating direction indicated by means of an arrow in FIG. 2.

For removing the clamping chuck 4 from the holding device 3 of thespindle 1, the clamping chuck and the spindle are rotated in a directionopposite to that during the insertion, whereby the frictional engagementis released and the clamping chuck can be removed. For the rotation intoand out of the frictional engagement, the clamping chuck 4 can beprovided with a key face which is not shown and to which a suitable toolcan be applied.

FIG. 3 illustrates the principle of the endeavored compensation ofeccentricities and unbalanced masses: Let it be assumed that the holdingdevice 3 has an eccentricity “a” or an unbalanced mass with the moment(size times distance from the axis of rotation 19 of the spindle) of “a”in the indicated direction. The clamping chuck 4 has an eccentricity “b”or an unbalanced mass with the moment “b”. The clamping chuck 4 has theholding device 3 and rotated about the angle W into frictionalengagement such that the direction of its eccentricity or unbalancedmass is as precisely as possible situated opposite that of the holdingdevice with respect to the axis of rotation 19. As a result, theeccentricities or unbalanced masses “a” and “b” compensate one anotherwith the exception of the residual amount “c” of a resultingeccentricity or unbalanced mass 20.

For reasons of clarity, FIG. 2 shows profiles 11, 12 with only threewedges 13 and 15. In order to permit a more precise compensation ofeccentricities or unbalanced masses, the profiles 11, 12 areadvantageously provided with more than three, preferably with six wedgeswhich permit an inserting of the clamping chuck in positions swivelledby 60° respectively.

The clamping chuck 4 is inserted with a “lead” in the sense that itsmarking 18 during the counterclockwise rotation can move in thedirection of the marking 17 on the receiving device 3. In this case, thejoining gap is first eliminated and then the frictional engagement isachieved with such a high contact pressure that the machining torque canbe absorbed. In this frictional engagement, the clamping chuck 4 canthen be rotated still farther until the markings 17, 18 are situatedapproximately opposite one another. As a rule, a rotating angle of up to30° is available for this rotation so that the markings 17, 18 andtherefore the eccentricities or unbalanced masses to be compensated canbe adjusted to be opposite one another up to an angular deviation of±15°.

In the same manner as with respect to the above-described clamping chuck4, according to FIG. 4, a clamping sleeve 21 for the holding of a tool,such as a milling tool 22, can also be inserted into the holding device3 of the spindle 1. For this purpose, the clamping sleeve 21 has on itsessentially cylindrical holding surface 23, the profile 11 adapted tothe profile 12 of the holding device 3.

According to the invention, the clamping sleeve 21 has a profile 25 ofthe described type for the holding of the tool 22 provided with anadapted profile 26 also in its centric receiving device 24 for the tool22. These profiles 25/26 facilitate and accelerate only the exchange oftools in the clamping sleeve and ensure a largely centric receiving ofthe latter in the clamping sleeve 21 as well as in the receiving device3 of the spindle 3; by means of these profiles—as described above forthe clamping chuck/holding device pairing of the spindle—,eccentricities or imbalances between the clamping sleeve and the toolcan also be reduced.

The inserting and removing of the clamping sleeve 21 into and from theholding device 3 of the spindle and of the tool 22 into and from theclamping sleeve takes place as described with respect to the clampingchuck 4. In the same manner, a tool 22 can removed from the clampingsleeve 21 in the case of wear or damage and can be replaced by anothertool. The tools 22 are advantageously provided with key faces 29 towhich tools can be applied for the exchange.

In the embodiment of FIG. 5, the tool is a drill 27 which, during themachining, must transmit not only torque but also shearing force in thedrilling direction. So that it can securely transmit this shearing forceto the clamping sleeve 21, the receiving bore 24 of the clamping sleeveis constructed as a pocket bore on the bottom of which the drill restswith the end of its shaft. The clamping sleeve 21 is also supported bymeans of an adjusting screw 28 on the rear wall of the bore of theholding device 3 of the spindle 1. By means of this adjusting screw 28,the drilling depth of the drill 27 can be adjusted. Naturally thisadjustment can also be achieved by placing spacer pieces between theface of the clamping sleeve 21 and the bottom of the bore of the holdingdevice 3.

Particularly during the holding of tools, such as milling tools 22according to FIG. 4 which, during the machining, must transmit nosignificant shearing forces, the holding force is as a rule sufficientwhich is generated by the frictional engagement in the profile pairings11/12 and 25/26. At least, no special measures are required here withrespect to the securing against an axial displacement. However, in mostother cases, the frictional engagement can also be selected to be sohigh that by way of the profile pairings 11/12 and 25/26 alone,sufficient shearing and tensile forces can also be transmitted.

Thus, in the embodiment of FIG. 4, for adjusting the position of thetool 22 in the axial direction, the clamping sleeve 21 is pushedcorrespondingly deeply into the holding device 3 of the spindle 1 and isfastened by the mutual rotating of the clamping sleeve and the holdingdevice. In the axial direction, the profile surfaces are advantageouslyso wide that also, in the case of the lowest provided insertion depth, asufficiently high frictional engagement is achieved for transmitting therequired torques and forces.

In some cases, it may be advantageous to let the wedges extend in asteeply helical manner. This can achieve that a force resulting from acircumferential force and from a shearing force acts in the axialdirection approximately in the slope direction of the wedge surfaces.

The direction of the slope of the wedges 13 and 15 is advantageouslyselected in both profile pairings 11/12 and 25/26 such that thetightening of the profile pairings takes place in that rotationaldirection in which during the operation the torque is transmitted.However, the frictional engagement can easily be selected to be so highthat also in the opposite rotating direction a holding moment will existwhich exceeds to operating torque to be generated; a tool can thereforebe inserted in both rotating directions.

The amount of the frictional engagement can be determined by the slopeof the wedges 13 and 15, by their width, by the material pairing of theinteracting profiles and by the tightening torque. The slope of thewedges 13, 15 is advantageously between 1:50 and 1:500. Larger slopesare assigned to smaller diameters, for example, that of the drill 27;smaller slopes, in contrast, are assigned to larger diameters. As theresult of the arrangement of the three wedges 13, 15 preferably with thesame spacing along the circumference, an advantageous centering effectis achieved; however, as mentioned above, different numbers of wedges onthe circumference are also contemplated.

The wedge-shaped profiles 11, 12 and 25, 26 in the holding device 3 andon the clamping chuck 4 or the clamping sleeve 21 and on a tool 22, 27can be produced, for example, by grinding. The surfaces of the wedges13, 15 may be cylindrical.

However, advantageously, they follow a logarithmic spiral because, inthis case, the whole surfaces rest against one another with the samecontact pressure and, as a result, an optimal frictional engagement andan optimal centering are achieved also in the case of a one-sided load.

It is understood that the holding of the clamping chuck 4 or of theclamping sleeve 21 is possible also in a kinematic reversal of theillustrated embodiment in that the holding device 3 carries the profile12 on its outer circumference and the clamping chuck 4 or the clampingsleeve 21 carries the profile 11 in a bore.

Although the invention has been described and illustrated in detail, itis to be clearly understood that the same is by way of illustration andexample, and is not to be taken by way of limitation. The spirit andscope of the present invention are to be limited only by the terms ofthe appended claims.

What is claimed is:
 1. Process for compensating eccentricities and/orimbalances of rotating parts including a spindle of a turning machineand a clamping device which is one of a clamping chuck, a clampingsleeve, a workpiece or a tool which is received on the spindle,comprising the acts of: determining the eccentricity and/or theimbalance of the rotating parts, joining the rotating parts in such amutually angular position that, while reaching a sufficient frictionalengagement, the rotating parts are rotated into an angular position inwhich the determined eccentricities and/or imbalances are situatedapproximately diametrically opposite one another with respect to theaxis of rotation of the spindle.
 2. Process according to claim 1,wherein holding surfaces are provided on the rotating parts which haveprofiles which are coordinated with one another in pairs and which eachhave at least two wedges which rise over respective imaginarycylindrical reference surfaces radially with each respective wedgerising toward the outside or toward the inside of the imaginarycylindrical reference surfaces and each again drop steeply back to therespective reference surfaces, and are offset by equal angles in thecircumferential direction and have a joining gap in a joining position.3. Process according to claim 2, wherein the slope of the wedges isbetween 1:50 and 1:500.
 4. Process according to claim 2, wherein a totalof three wedges of a profile pairing is provided.
 5. Process accordingto claim 2, wherein a total of six wedges of a profile pairing isprovided.
 6. Process according to claim 2, wherein a rising direction ofthe wedges of the profile pairings is such that, during the machining ofa workpiece, the wedges endeavor to slide up on one another.
 7. Processfor compensating eccentricities and/or imbalances of rotating parts tobe connected, said rotating parts including one of a spindle of aturning machine, a clamping device, a clamping chuck, and a clampingsleeve on a first section and said rotating parts including one of aworkpiece and a tool on a second section, which are received in therotating part on the first section, wherein said rotating parts haveholding surfaces which are provided with profiles coordinated with oneanother in pairs and which each have one of three and six wedges whichrise over imaginary cylindrical reference surfaces radially toward theoutside or toward the inside of the imaginary cylindrical referencesurfaces and each then drops steeply back to the reference surfaces, andwhich are offset by equal angles in the circumferential direction andhave a joining gap in a joining position, wherein the slope of thewedges is between 1:50 and 1:500, the process comprising the steps ofdetermining the angular position of eccentricity and/or the imbalance ofrespective rotating parts of the first and second section to beconnected, joining the rotating parts in such a mutually angularposition that, while reaching an engagement of the coordinated profilesof the holding surfaces, the eccentricities or unbalanced masses of therespective rotating parts to be connected being substantiallydiametrically opposite with respect to the axis of rotation of therotating parts, subsequently, twisting the rotating parts one againstthe other in a direction of more frictional engagement of thecoordinated profiles of the holding surfaces up to such a mutual angularposition of the respective rotating parts, that the determinedeccentricities and/or imbalances are situated diametrically opposite oneanother with respect to the axis of rotation and into a position of anoptimal compensation of the eccentricities or unbalanced masses.